PDPN and glioblastoma: PDPN‐overexpressed GBM cells secrete PDPN‐containing EVs, followed by phagocytosis by unpolarized M0 macrophages, which induce immunosuppressive polarization of macrophages, manifested by the release of immunosuppressive cytokines, ERK phosphorylation activation, diminished MHC II expression, and incompetence to CD4+ T activation.